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Hypohidrotic Ectodermal Dysplasia
Tuesday, 11 January 2005
Tuesday, 11 January 2005
Hypohidrotic Ectodermal Dysplasia (HED) is an inherited condition characterized by a reduced ability to sweat (hypohydrosis), missing teeth, and sparse hair.
HED is estimated to occur in 1 out of 20,000 children. The majority of affected children are boys but girls can also be affected, although somewhat less severely. All races and ethnicities are affected equally.
Signs and Symptoms
At birth, babies with HED may have excessively peeling skin. As they grow, they are noted to sweat less than other children. This is due to a reduced number of sweat glands. Sweating is important to help the body keep cool in hot environments. Decreased sweating puts children with HED at risk for hyperthermia
(elevated body temperature). Signs of overheating include headache, irritability, lethargy, fainting, and muscle cramps. Teething is often delayed by 6-12 months and can be abnormally shaped (small cone-shaped teeth). Missing teeth and cavities are also common.
Children with HED also have light-colored skin and reduced oil production by the skin. As a result, affected children have dry skin and even chronic eczema. The skin around the mouth and eyes may appear darkened and wrinkled. Children with HED have a dry mouth and a raspy voice because they don’t make enough saliva and mucus. The interior lining of the nose can become dry, cracked and scabbed. Children with HED have flat, depressed noses, or “saddle” shaped noses. The child may also experience a decreased sense of smell and taste. A prominent forehead, large chin, and thick lips are also characteristic of people with HED.
Scalp and body hair are sparse, light-colored, and slow-growing. Hair tends to be brittle and breaks easily. Dandruff is common. Some children may develop no hair at all on their heads. The arms and legs may also be without hair, but facial hair is normally present. Nails are thin and brittle. The nipples are often underdeveloped and females may experience poor milk production later in life.
The immune system is affected as well. Children with HED may have asthma and recurrent respiratory infections. Constipation may also occur. Children with HED have normal intelligence.
HED is not contagious or preventable. It is an inherited genetic disorder. Ninety five percent of children with HED have the X-linked form, while the remaining 5% have either the autosomal recessive or autosomal dominant form. X-linked HED is caused by genetic changes (mutations) on the X chromosome. The autosomal recessive and dominant forms are caused by mutations on chromosomes 1 and 2, respectively. These genes are important for the proper development of skin tissues. X-linked HED largely affects boys, as girls carry two X chromosomes. Boys usually inherit the genetic mutation from their mothers, who typically have mild symptoms or none at all. When women are carriers of the mutated gene, 50% of their sons will have HED. All of the daughters of an affected male will be carriers, but none of the sons will be affected. In some cases, spontaneous mutations may be responsible for HED. Autosomally-inherited HED affects boys and girls equally.
An iodine sweat test may be used to diagnosis HED. In this test, iodine is applied to the skin and the temperature of the room is increased to induce sweating. The iodine solution changes color when exposed to sweat and can be used to determine the amount of sweating at its location. A skin biopsy is the best method to confirm the diagnosis of HED. Genetic testing and prenatal diagnosis are also available.
There is no cure for HED. Treatment aims to preventing hyperthermia. Hot climates and exposure to heat must be minimized. Fevers must be treated promptly. Access to drinking water is essential in warm weather. An air conditioner and a humidifier are recommended to have in the home. The child may prefer to sleep naked.
It is important to keep the skin well-moisturized. Skin moisturizers are essential for the management of eczema and dry skin. Mild, non-drying soaps should be used. Artificial tear drops are important to use to keep the eyes from drying out. Rinsing the nose with salt water can prevent scabbing. Dental treatment must begin early. Dental implants, orthodontic therapy and dentures may be necessary.
HED generally has a very good prognosis. Skin problems can vary in severity but they do not affect life span, which is normal in individuals with HED. Cosmetic complications can be reduced by aggressive daily skin care. Hyperthermia is the most feared complication because it can lead to heatstroke, which can be fatal. Participation in sports must often be reduced.
Connect with other parents
In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.
National Foundation for Ectodermal Dysplasia
Provides information, support, networking, and fundraising.
Sarah Moody Foundation
Provides news and networking.
March of Dimes Birth Defects Foundation
Non-profit organization providing support groups, education, information about research studies, counseling, and family networking.
NIH/National Institute of Arthritis and Muscluskeletal and Skin Disease
Provides outreach programs and clinical studies.
National Oral Health Information Clearinghouse (NOHIC)
Provides information, news, clinical trials.